In airlift terms, the C-17A Globemaster III has arguably made the biggest single impact to Western Air Forces in the 21st Century thus far – and will likely hold this claim for the next decade. While it was conceived for the United States Air Force in the 1980s and introduced to service in the 1990s, its acquisition by nations including Canada, Australia, and the United Kingdom has given Western Air Forces its first real appreciation of modern strategic airlift. For the USAF, which arguably wrote the book on strategic military airlift, has also benefited significantly from the C-17A’s tactical airlift talents. Elsewhere, the aircraft has been capitalised upon by NATO, India, the UAE, Qatar, and Kuwait.
With the production line closing in 2015, it is unlikely that we will ever see new Globemaster airframes constructed beyond the 279 that were delivered by McDonnell Douglas/Boeing (and indeed, a small number have been relegated to a museum or lost in an accident). This is not to say that we will not see new C-17 variants, especially if the Globemaster lives to see service past 2040, half a century after its first flight. Getting the airframe to that point (and beyond) however, will require careful attention and development.
Certainly, the C-17A has been no stranger to being developed over its 25-year history thus far. With a production spanning 15 years, older C-17As have been upgraded to match their newer kin with radios, weather radar, and combat lighting. A centre wing fuel tank was fitted to C-17As constructed after 2001 to extend the aircraft’s range, and in recent years, aircraft have been equipped with Large Aircraft Infrared Countermeasures and improved communications systems. Early Block Upgrades to the C-17A addressed design flaws in the original production aircraft – more recent ones have addressed issues of obsolescent aircraft systems and ensured fleet commonality.
More upgrades are projected. The C-17A’s Heads-Up Display (HUD) dates back to the early 1990s, and in 2011, Elbit was announced as the winner of the project to deliver a replacement HUD (although no public announcements have emerged since then). Trials are underway to add airflow strakes to the aircraft’s fuselage as a means of decreasing drag. Options to add Link-16 and more advanced satellite communications antennas are also being explored.
How else might we see the C-17A mature in the next 30 years?
Numerous aircraft go through their service career with modest increases in capability to allow them to continue in their intended role. Indeed, it is arguable that the C-17A has maintained this track to date with the changes it has undergone thus far. The purpose of such upgrades are not so much to advance the aircraft beyond the original design intent, but more to ensure it remains compatible with current/immediate operating practices and airborne environments. Compatibility with any new Identification Friend or Foe (IFF) or battlespace networking systems, or global air traffic control management systems, are examples of this.
The aircraft’s cockpit ergonomics are still reminiscent of its early 1990s design, so it is not unreasonable to expect a major Mid-Life Update program that would improve the quality of cockpit displays, communications management, and other avionics. Newer airlifters such as the C-130J and A400M are equipped with larger HUD units and displays that can incorporate digimaps or other navigational data. A precedent for upgrading the C-17A exists, whereby old air mobility platforms (including the C-130H, KC-135 and C-5) have replaced their ‘steam gauge’ instruments and analogue controls with LCD screens and digital displays. Replacing these systems means eliminating obsolescence and ensuring the cockpit ergonomics have greater commonality with the wider air mobility and training fleet, and potentially improving the ease with which software updates can be applied to the aircraft.
Slightly More Ambitious Options….
The upgrades mentioned above were in large part to ensure the C-17A maintained pace with its operating environment. More ambitious upgrades, however, would provide new ways of performing its current mission. Evidence exists within existing air mobility platforms like the KC-135, which has been upgraded with navigation systems that now allow the aircraft to operate without a Navigator.
How could this apply to the C-17A? It is hard to judge this, as it is largely contingent on the technology that will be available to us in the next 15 years. It is easy to imagine a technology that has been applied to the A400M and C-130J being rolled out on the C-17A. It is harder to imagine the impact that newer and emerging technology – such as helmet-mounted displays, external sensors, and personal devices – will have. New tactical airlifters benefit from infrared cameras that allow landings to be comfortably made of poor visibility conditions. Whether such technology has an application on the C-17A remains to be seen.
Likewise, the C-17A was revolutionary for its time by its use of a dedicated loadmaster station inside the cargo hold, a feature which has been capitalised by other airlifters. A future C-17A upgrade might extend on this further, allowing the loadmaster to control environmental conditions and cargo locks in the cargo hold with a personal electronic device, or direct automated aircraft loading equipment.
The High-End Option
High-end changes are easy to debate, being linked to systems on the aircraft that will become wholly inefficient or unsustainable during the aircraft’s life-of-type. These changes would be sufficient to mean the end of the C-17A as we know it today, delivering us a noticeably different aircraft – a C-17B or C-17C, for example.
Again, existing examples allow us to make educated guesses about the future, not only about the systems that are applied and upgraded but the causes for doing so. The C-5M Super Galaxy is the product of a program upgrade older C-5As and Bs with new engines, new avionics, improved cargo ergonomics, and most importantly, greater aircraft reliability. It essentially brings an aircraft design whose systems have their roots in the late 1960s and gives a 21st-century solution. The net result is a Galaxy with a shorter take off distance and better climb rate, as well as extended range. While the C-17A is reliable now, we can expect to question its relative performance in the future, especially if the expectation is for the aircraft to beyond a 30-year lifespan. Upgrading the C-17A could prove less expensive than embarking upon an all-new airlift replacement, too.
Achieving this could take some paths. Replacing the engines on the aircraft, especially in light of advances in civilian airliner power plants, would be the most obvious choice. It could yield a Globemaster that is more fuel efficient or carries heavier payloads, and the C-17A’s existing power plant – the Pratt & Whitney F117 – is a militarised version of the turbofan that powers Boeing 757s. One issue here, however, is that C-17A engines are required to perform across a different spectrum than a stock civilian airliner. This means a simple transplant of a civilian power plant will not likely address the C-17A’s performance needs.
Another potential upgrade could be to the C-17A’s winglets, which were revolutionary for their time in 1991. This feature improves the wing’s performance, reducing drag and improving fuel efficiency in a cruise. Today, the C-17A’s winglets appear clunky in comparison to modern airliners which possess ‘blended winglets’ that enhance fuel burn. Ensuring the Globemaster can cruise efficiently, extending its range and lowering its operating costs, are likely to be a significant consideration for how the aircraft is upgraded into the future.
Other considerations for a potentially major upgrade to the Globemaster might include those options put forward by Boeing during the late 2000s to improve the aircraft’s tactical performance. Considerations for the ‘C-17B’ including a new higher thrust powerplant, double-slotted flaps, additional centre-line landing gear, and precision landing systems. It is arguable that the additional weight of some of these systems would come at a cost to the aircraft’s range and cruise efficiency. On the other hand, a sub-fleet of C-17s optimised for tactical performance to deliver payloads that can not be accommodated in a C-130 (and are unable to be transported over long ranges by future heavy vertical lift)
Examining options for the Globemaster’s future may see it called to perform roles that are well outside the traditional airlift roles that the aircraft performs today. Few would argue that the C-17A’s talents are best applied to providing dedicated strategic and tactical airlift. The external surfaces of a C-17A, however, provide significant ‘real estate’ for discrete sensors and antennas, and the aircraft’s interior likewise has space that would allow it to fulfil support functions for C4I and ISR – especially if the terminals for such roles are significantly smaller and modularised, contrasting with the fixed workstations that fill C-135 and Boeing 707 variants operated by the USAF. Today, other platforms (such as those based on commercial airliners) might conceivably fulfil this role more efficiently and effectively than a Globemaster. However, future requirements – especially those that call for an aircraft to deliver personnel and vehicles, then remain near provide immediate support – might dictate that the C-17 is the aircraft for the job.
The last consideration for the Globemaster receiving a ‘high-end’ upgrade is that it might pick up new roles not even in service today. The aircraft has been mooted as a potential ‘Drone Mothership’ in a battlespace, deploying them to perform a range of ISR, attack, and strike missions. Alternatively, the C-17A’s cargo bay has considerable space for batteries and other systems that would employ high-energy weapons.
Where the Globemaster ultimately fulfils any of these roles is anyone’s guess – while the technology is being developed, it is by no means about to be applied to the C-17A. Once said technology is mature, there are no guarantees that the C-17A will be the best jet for the job.
The Likely Options
At a minimum, progressive upgrades will need to be applied in the future to ensure the C-17A can continue to be operated. The crew stations are likely to be developed over time, as are the aircraft’s avionics, communications and networking systems. Foreign operators should bear these developments in mind – on the one hand, the upgrading of their aircraft is likely to have a greater impact on the number of aircraft they have available. On the other hand, such programs are an avenue for them to suggest development roadmaps that can be shouldered by Boeing and USAF. Exploring these avenues, however, would have to be a modest process. However, it is unlikely that an entirely new C-17 variant will be developed if only one smaller operator is guaranteed to require it.
With that in mind, the Globemaster’s future development is likely to be informed by three things – keeping the airframe viable, the USAF’s appetite to embark on upgrade programs, and Boeing’s willingness to provide options. Lockheed Martin’s C-5M program provides an excellent example of where the C-17A can go with such updates, replacing aircraft structures and systems that have become tired and unreliable while also meeting demands of the customer to capitalise on generational changes in engine, avionics, and ergonomic technology. Indeed, the C-5M in some respects feels like it carries some of the best features of a C-17A (except the HUD and fighter control stick).
Strategic airlift development, however, emphasises the importance of cruise efficiency and performance, which is often largely dependent on reductions in the aircraft’s weight and improvements in a power plant. Such upgrades are easy to forecast in the C-17A’s future. The more ‘creative’ upgrades for the Globemaster will be in how it is required to perform tactical roles in future – or approach brand new problems.
This post first appeared at Rubber-Band Powered Blog.
Header Image: A C-17 arrives with GEOS-O on board at the Shuttle Landing Facility. (Source: Wikimedia)